We present amodel that allows the analysis of the behavior of ferroelectric materials in a wide range of frequencies. A common approach to the transient properties of dielectrics based on differential equations was extended by an additional term representing the non-linearity of the material. Our model was designed with respect to a stable discretization. Based on a transient formulation, our model allows the analysis of the device in the time regime. This includes the simulation of relaxation, thus enabling an exact analysis of the read and write cycles of ferroelectric nonvolatile memory cells. As an example the parameters for a specific device were extracted using measured data and an excellent correspondence was achieved.